Creating volumetricaly layered materials in Cycles
If you mean what I think you mean, then yes it is possible.



Is this what you mean? It is one object, but there are different materials in different places.

This is the node setup:


The way this works is I separate the object into its X, Y, and Z coordinates. I then select how much of these coordinates I would like to be one material (In this case emission, shown by the white in the colour ramp nodes. This allows layers of different materials within the volume.

If you require these layers of materials to be place at random points, you can just plug in the red component from a noise node into the factor for the mix node as shown below:


I have also passed it through a brightness and contrast node to emphasize the border between the two materials.

Here is the result:


You can achieve really interesting results if you use different types of textures:


Node setup:


Another interesting result I came up with:


Hope this helps you :)

EDIT:

Here is the technique applied for a layered material:



Here is the node setup:


To achieve this layered effect simply change the color ramp. the black bars on each side of the color ramps indicate the thickness of the outer layer. However, this only works with volumetric materials like emission, volume scatter and volume absorption. To layer multiple surface materials they can simply be mixed/added. This will however not work with visible thickness as they are surface shaders and as such only appear on the surface and not in the volume.

That being said, the glass, refraction and transparent shaders can yield some interesting results with the fresnel node.

E.g: Layered glass:


Node setup:


The color ramp may look completely white but it is actually 1.1 and 1.45, set to constant.

However, a see through surface shader may be used together with a volumetric to achieve a different type of layered effect.

Volume scatter in glass:


Emission in translucent:


Generic node setup for volumetric within surface:


The volumetric can be replaced with any of the volumetric shaders shown above.

Hope all this additional info helps :D

EDIT 2:

Just ended up making the 'button' with this technique, thought I'd put it here: